Analysis and computation of the oil film thickness between the piston ring and cylinder liner of an internal combustion engine

A study of the essential features of piston rings in the cylinder liner of an internal combustion engine reveals that the lubrication problem posed by it is basically that of a slider bearing. According to steady-flow-hydrodynamics, viz. Image the oil film thickness becomes zero at the dead centre positions as the velocity, U = 0. In practice, however, such a phenomenon cannot be supported by consideration of the wear rates of pistion rings and cylinder liners. This can be explained by including the “squeeze” action term in the

Running-in wear of a compression ignition engine: Factors influencing the conformance between cylinder liner and piston rings

The conformance between the liner and rings of an internal combustion engine depends mainly on their linear wear (dimensional loss) during running-in. Running-in wear studies, using the factorial design of experiments, on a compression ignition engine show that at certain dead centre locations of piston rings the linear wear of the cylinder liner increases with increase in the initial surface roughness of the liner. Rough surfaces wear rapidly without seizure during running-in to promote quick conformance, so an initial surface finish of the liner of 0.8 μm c.l.a. is recommended. The linear wear of the cast iron liner and rings decreases with increasing load but the mass wear increases with increasing load. This discrepancy is due to phase changes in the cast iron accompanied by dimensional growth at higher thermal loads. During running-in the growth of cast iron should be minimised by running the engine at an initial load for which the exhaust gas temperature is approximately 180 °C.

High temperature mechanical properties of thermal barrier coated superalloy applied to combustor liner of aero engines

High temperature load controlled fatigue, hot tensile and accelerated creep properties of thermal barrier coated (TBC) Superni C263 alloy used as a candidate material in combustor liner of aero engines are highlighted in this paper. Acoustic emission technique has been utilised to characterise the ductile-brittle transition teperature the bond coat. Results revealed that the DBTT (ductile to brittle transition temperature) of this bond coat is around 923 K, which is in close proximity to the value reported for CoCrAlY type of bond coat. Finite element technique, used for analysing the equivalent stresses in the bond coat well within the elastic limit, revealed the highest order of equivalent stress at 1073 K as the bond coat is ductile above 923 K. The endurance limit in fatigue and the life of TBC coated composite under accelerated creep conditions are substantially higher than those of the substrate material. Fractographic features at high stresses under fatigue showed intergranular cleavage whereas those at low stresses were transgranular and ductile in nature. Delamination of the bond coat and spallation of the TBC at high stresses during fatigue was evident. Unlike in the case of fatigue, the mode of fracture in the substrate at very high stresses was transgranular whereas that at low stresses was intergranular in creep.

Advances in the analysis and design of concrete structures, metal containments and liner plate for extreme loads

The material presented in this paper summarizes the progress that has been made in the analysis, design, and testing of concrete structures. The material is summarized in the following documents: 1. Part I - Containment Design Criteria and Loading Combinations - J.D. Stevenson (Stevenson and Associates, Cleveland, Ohio, USA) 2. Part II - Reinforced and Prestressed Concrete Behavior - J. Eibl and M. Curbach (Karlsruhe University, Karlsruhe, Germany) 3. Part III - Concrete Containment Analysis, Design and Related Testing - T.E. Johnson and M.A. Daye (Bechtel Power Corporation, Gaithersburg, Maryland USA) 4. Part IV - Impact and Impulse Loading and Response Prediction - J.D. Riera (School of Engineering - UFRGS, Porto Alegre, RS, Brazil) 5. Part V - Metal Containments and Liner Plate Systems - N.J. Krutzik (Siemens AG, Offenbach Am Main, Germany) 6. Part VI - Prestressed Reactor Vessel Design, Testing and Analysis - J. Nemet (Austrian Research Center, Seibersdorf, Austria) and K.T.S. Iyengar (Indian Institute of Science, Bangalore, India).

Gypsum treated fly ash as a liner for waste disposal facilities

Fly ash has potential application in the construction of base liners for waste containment facilities. While most of the fly ashes improve in the strength with curing, the ranges of permeabilities they attain may often not meet the basic requirement of a liner material. An attempt has been made in the present context to reduce the hydraulic conductivity by adding lime content up to 10% to two selected samples of class F fly ashes. The use of gypsum, which is known to accelerate the unconfined compressive strength by increasing the lime reactivity, has been investigated in further improving the hydraulic conductivity. Hydraulic conductivities of the compacted specimens have been determined in the laboratory using the falling head method. It has been observed that the addition of gypsum reduces the hydraulic conductivity of the lime treated fly ashes. The reduction in the hydraulic conductivity of the samples containing gypsum is significantly more for samples with high amounts of lime contents (as high as 1000 times) than those fly ashes with lower amounts of lime. However there is a relatively more increase in the strengths of the samples with the inclusion of gypsum to the fly ashes at lower lime contents. This is due to the fact that excess lime added to fly ash is not effectively converted into pozzolanic compounds. Even the presence of gypsum is observed not to activate these reactions with excess lime. On the other hand the higher amount of lime in the presence of sulphate is observed to produce more cementitious compounds which block the pores in the fly ash. The consequent reduction in the hydraulic conductivity of fly ash would be beneficial in reducing the leachability of trace elements present in the fly ash when used as a base liner. (C) 2010 Elsevier Ltd. All rights reserved.

Clay mineral liner system for leachates containing organic contaminants

A conventional liner with a good performance against inorganic contaminants with a minimal hydraulic conductivity does not usually perform well for retention/removal of leachates containing organic contaminants. Organic modification of clay can render the naturally organophobic clay tobe organophilic. Incorporation of modified organo clay along with unmodified inorganic clay in liner systems can overcome the inherent incompatibility of conventional liners to organic contaminants and can increase organic sorption. The performance of commercially available organo clay and natural bentonite and mixtures of them in different pore fluids has been studied. It is found that the properties of mixtures improve with increase in organically modified clay particularly in non aqueous fluids from the considerations of liner application.

Index properties of illite-bentonite mixtures in electrolyte solutions

Bentonite, commonly used for liner constructions in waste containment systems, possesses many limitations. Illite or illite containing bentonite has been proposed as an alternative material for liner construction. Their properties in different types of pore fluids are important to assess the long-term performance of the liner. Further, the illite-bentonite interaction occurs and changes their properties. The effect of these interactions is known when the pore fluid is only water. How their properties are modified in electrolyte solutions has been brought out in this paper. The index properties have been studied since they give an indication of their engineering properties. Due to reduction in the thickness of the diffused double layer and consequent particle aggregation in bentonite, the effect of clay-clay interaction reduces in electrolyte solutions. In electrolyte solutions, the liquid limit, the plasticity index, and free swell index of bentonite are lower than illite. The plasticity index of bentonite is further reduced in KCI solution. Clays with a higher plasticity index perform better to retain pollutants and reduce permeability. Hence, the presence of both illite and bentonite ensures better performance of the liner in different fluids.

Fly ash as a pre-filter material for the retention of lead ions

Clay liners have been widely used to contain toxic and hazardous waste materials. Clays absorb contaminant cations due to their exchange capacity. To improve the performance of the clay liner, fly ash, a waste material arising from the combustion of coal has been studied as a pre-filter material. In particular, the retention of lead by two different fly ashes was studied. The influence of pH on retention as well as leaching characteristics are also examined. The results obtained from the retention experiments by the permeameter method indicate that fly ash retains the lead ions through precipitation in the pores as well as onto the surface when the ambient pH value is more than 5.5, and through adsorption when the pH value is less than 5.5. It has been observed that fly ash did not release the retained lead ions when the pH value is between 3.5 and 10.0. Hence, the retention of lead ions by fly ash is likely to be permanent since the pH of most of the municipal landfill leachates are within 3.7 to 8.8. However, for highly acidic or alkaline leachates, the retained ions can get released.

Influence of pH on the retention of heavy metal ions by fly ash

Clay liners have been widely used to contain toxic and hazardous wastes. Clays adsorb the contaminant cations due to their exchange capacity. To improve the performance of the clay liner, fly ash, a waste material arising out of combustion of coal has been studied as a pre-filter material. The results indicate that fly ash has the potential to retain heavy metal ions. This study concerns the retention of zinc by fly ash. The influence of pH on retention as well as leaching characteristics are examined. The results obtained from the retention experiments by permeameter method indicate that fly ash retains the zinc ions through precipitation in the pores as well as onto the surface when the ambient pH value is more than 6.9, and only through adsorption when the pH value is less than 6.9. It has been observed that fly ash did not release the retained zinc ions when the pH value is between 3.5 and 10.0. Hence, the retention of zinc ions by fly ash is likely to be permanent since the pH of most of the landfill leachates are between 3.7 to 8.8.

Supramolecular hydrogen-bonded structures in organic amine squarates

Structures of monohydrogen squarates of methylamine, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, N,N'-diemethylpiperazine and N,N,N,N-tetramethylguanidine have been studied in detail. The supramolecular hydrogen-bonded molecular networks are formed by the monoanion of squaric acid by itself or in association with the parent acid. Three types of hydrogen-bonded motifs are observed in these compounds, namely a liner chain, a cyclic dimer and a cyclic tetramer. These hydrogen-bonded motifs formed by the squaric acid species interact with the amine through N-H...O hydrogen-bonding and give rise to predominantly layered structures, while some of them also exhibit three-dimensional structures. Two of the monohydrogen squarate structures also exhibit pi-pi interactions between two squarate rings. The various hydrogen-bonding parameters in the amine squarates are discussed at length. (C) 2002 Elsevier Science B.V. All rights reserved.

Precoder Designs for MIMO Broadcast Channels with Imperfect CSI

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Evaluation of bentonite and sand mixtures as liners

Compacted clay liners are widely used for waste contaminant facilities because of their low cost, large leachate attenuation capacity and resistance to damage and puncture. Commonly used bentonite possess many limitations such as high swelling and shrinkage potential, sensitivity to waste fluid characteristics etc. The paper proposes the use of bentonite-sand mixture containing optimal clay content as liner material. It has been brought out, based on detailed geotechnical investigations, that a mixture containing only about 20 to 39% of bentonite is more suited than the clay alone and they possess.